Nail-driving mechanism



Sept. 22, 1953 c. J. BACON ET AL NAIL-DRIVING MECHANISM Filed Sept. 23, 1950 Gi'tormg I will! all Patented Sept. 22, 1953 NAIL-DRIVIN G MECHANISM Clinton J. Bacon, Los Angeles, and Samuel J. Kent, Van Nuys, Calif., assignors to Nu-Matic Nailer, Inc., Los Angeles, Calif., a corporation of California Application September 23, 1950, Serial No. 186,414

3 Claims. 1

This invention relates to nail-driving mechanism more particularly adapted for use in nailing machines. This application is a continuation-in-part of our pending application Serial No. 737,510, filed March 27, 1947, the same issuing on March 27, 1951, as Patent No. 2,546,354.

An object of the present invention is to provide a nail-driving mechanism that employs a pneumatically reciprocated hammer which reciprocates only during the nail-driving movement of the mechanism to thereby eliminate unnecessary percussive movements of the hammer, the same resulting in increased life of the mechanism.

The present mechanism employs air-actuated hammer means of conventional form, the same being equipped with a trigger to control flow of compressed air thereinto. Such hammer means depend on alternately applying compressed air to the opposite end of the percussive element or hammer to reciprocate the latter while the trigger is held open. However, the recovery stroke or movement of the hammer can occur only when the air supplied for such movement is trapped against escape from the operative end of the cylinder of the hammer means.

Accordingly, another object of the invention is to provide novel means afiixed to theoperating end of conventional reciprocating hammer means that traps air only while driving a nail or the like and moves towards and reaches an airventing position that stops the operative movement of the hammer when the nail is driven to the depth desired.

The invention also has for its objects to provide such means that are positive in operation, convenient in use, easily installed in a working position and easily disconnected therefrom, economical of manufacture, relatively simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. However, the drawings merely show and the following description merely describes one embodiment of the present invention, which is given by way of illustration or example only.

In the drawings, like reference characters designate similar parts in the several views.

Fig. l is a longitudinal sectional view, partly die showing the machine in the contracted position at the end of the nail-driving operation.

Fig. 3 is an enlarged fragmentary longitudinal sectional View, showing the nail-driving means in an intermediate position and at the start of the nail-driving operation.

Figs. 4 and 5, to the scale of Fig. 3, are crosssectional views taken substantially on lines l l and 5--5, respectively, of Fig. 1.

The nailing machine that is illustrated comprises, generally, nail-driving mechanism it, stirrup means H for engagement by the foot of the user to hold the machine in operative position, a ball and socket connection !2 between the lower end of mechanism It! and stirrup I 5, enabling the user to angularly adjust mechanism H) to drive a nail at a desired angle, a tiltable nail hopper l3, means I4 connecting the hopper and the nail-drivingmechanism for tilting movement of the former during manual operation of the latter, escapement means !5 receptive of nails from the hopper and movable under control of means M to discharge a nail during each operative movement of the mechanism It, and guide means l6 for guiding nails so discharged to a position from which they are driven from the machine by the nail-driving mechanism iii.

The mechanism It! comprises, generally, a barrel I! to which the stirrup, hopper, escapement, and guide means are connected, a manually reciprocable air-actuated hammer means l8 telescopically engaged with said barrel, a nail driver element l9, and means 20 connecting the nail driver element 19 and the hammer means 8. The lower portion of hammer means l8 and the means 20 extendingdownwardly therefrom constitute a plunger that is reciprocable in barrel H.

In a manner similar to that disclosed in said pending application and assuming there is a. nail at 2! in the barrel 1! and that the hopper l3 has discharged nails onto a slideway 22 so that a nail 23 resides in escapement l5, the extended hammer means I8, from the position of Fig. 1, is depressed to bring the nail driver element l9 into engagement with the head of the nail at 2!. Toward the end of such downward movement of the hammer means, a cam 24 011 connection means l4 laterally transposes escapement means i5 and nail 23 thereon to effect discharge of said nail to fall through guide means It until the same comes to rest against the side of nail driver element It while the latter is in the process of driving nail 2! under the percussive force of compressed air entering hammer actuated means l8. It will be seen that from the initial angularly depending position of Fig. 1, the hopper l3 will be elevated to the position of Fig. 2, so that the same, through slot 25, deposits one or more additional nails onto slideway 22.

At the end of the nail-driving operation, the hammer means IB is pulled upwardly to restore the parts to the position of Fig. 1. During such movement, a cam similar to cam 24, but on the opposite side, returns the escapement toits initial position to receive a nail from slideway 22, or a return spring may be used for this purpose. Upon such movement, nail driver element [8' is withdrawn upwardly so that the nail resting thereagainst will fall into the lower end of body l1 and be held in the position, at 2| by a spring detent 26. The above-described cycle of operation is repeated to drive the new nail at 2|.

The present improvements deal primarily with the nail-driving mechanism l comprised of bar- I rel ll, hammer means l8, nail driver element [3, and connection means The barrel l1 comprises. an elongated tube 21 and nose piece 28' fitted into the lower end of said barrel and having an axial passage 29, said passage extending through the ball of the ball and socket connection I2. A lateral slot 30 in the nose piece 28 communicates guide means l6 and passage 29 so that nails may fall from the former into the latter. Detent 26 operates in said slot which, at its upper end is widened at 31 to pass the head of a nail falling to the position at 2!.

The conventional air-actuated hammer means 13 that is illustrated constitutes a plunger unit that is telescopically movable in barrel tube: 27 and comprises a conventional pneumatic tool 32 provided with an upper extension 33 that terminates in an upper handle 34. The latter, by means of a connection 35, is supplied with compressed air that enters a passage 36 under control of a normally closed valve in handle 38. Said valve is exemplified by a throttle lever or trigger 31 which, when. depressed, opens said. valve to flow of air from connection. to passage 36.

The pneumatic tool 32 comprises a cylinder 38 that has an. axial bore 39. that opens, at its lower end, in a passage 40 having a flared or chamfered end 4i (Fig. 3), a piston 42 reciprocable in said bore 39 and formed with a lower tip 43 that alternately strokes the upper end 54 of driving element i9 and is smaller in diameter than passage 40 to allow escape of air between itself andthe passage wall, a valve case 44 residing in an upper counterbore of cylinder 38, a valve 45 operable in said valve case, and a valve case lid 46 forming an upper extension of the valve case and enclosing the valve. Cylinder 38 is connected to a tubular housing portion 41 of extension 33 so that passage 36 is in communication withthe various bores and passages provided in the cylinder, valve case, and valve case lid. Since said. bores and passages are generally conventional, the same need not here be detailed except to say that air enters bore 38 to propel piston 42 downwardly to strike extension 54 of driver element l9 and alternately enters passage 48 to efiect upward retraction of said piston, both under control of valve 45. When there is air pressure in bore 39, above piston 42, passage 48 serves to exhaust air from said bore below the piston through one or more vents 49. When there is air pressure in passage 48, the upper end of the bore is opened to vents 49 and, as this pressure effects upward retraction of the piston, the latter uncovers an exhaust passage 58 that is open to vents 49 to efiect venting of the bore 39 below the piston preparatory to the next downward propulsion of said piston.

From the foregoing it will be seen that passage 40 must be closed in order that the air in the lower portion of bore 39 be trapped to be effective to retract piston 42 so that the same is rapidly reciprocated, otherwise the piston assumes its low position and remains there until passage 40 is closed at which time reciprocation is instituted.

In the present case, the element [9 and the means 20 eflect control of passage 40 during the cycle of operation of the nail-driving mechanism so that only when element I9 is engaged with a nail at 21' does piston 42 reciprocate and, after the nail has been. driven a predetermined distance, either flush or under flush, as shown in Fig. 2, reciprocation ceases. In this manner, much unnecessary wear on the tool 32 is obviated and, also, the operator is apprised of completion of the nail-driving operation so that he may release the trigger to conserve air and move the nail driver to the next point of application of a nail.

The nail driver element [9. comprises an. elongated member integrally formed at its lower end with a shank 5| freely operable in passage 28, an intermediate flange 52 larger in diameter than passage 40, and an upper head 53. having a sliding and air-sealing fit in said passage 40. The upper end of head 53, while retaining sliding and guiding fit with passage 40, is formed with one or more flats 54 that afiord passage of air from bore 39 outwardly through passage 40 when the lower end of said head 53 is withdrawn tov a position below the lower end of said passage 40.

The means 20 comprises a tubular member 55 that constitutes a lower extension of cylinder 38 and is. connected by threads 56 to a lower reduced end. 51 of said cylinder. The lower end 58 of member 55 hasan axial passage 58 that is aligned with passage 40 and through which shank 5| extends. Said. endv 58 afiords an upper shoulder 60 that engages. flange 52, as in Fig. 1. to suspend element [3. A set of openings 6| extend throughv end 58 of member 55 and are. arranged around passage 58. Said openings communicate the interior 62. of member 55 with barrel tube 21, said member at all times being engaged in said barrel tube. It is the lower end of the abovedescribed pneumatic tool 32 and the means 20 extending therefrom that constitute the plunger above-mentioned.

The extended. position of hammer means H! with respect to barrel I1 is limited, in this case, by engagement with said means 18 of a transverse pivot tube 63, the same. being part of the means l4 which connects hopper l3 and said means I8. Fig. 1 shows such engagement. The contracted position of means [8 with respect to barrel H is limited by a split collar 64 which, by means of threads 35 on cylinder 38, adjustably connects the. connecting means [4 and means l8. As seen. in Fig. 2, said. collar 64 abuts the upper end of barrel tube2'l to limit the. downward movement of means 18.

The adjustability of collar 64 is provided so that the nails may be driven as desired, either flush or under flush, as will be later apparent.

From the extended position of Fig. 1, it will be seen that the means 20 supports nail driver element by means of its flange 52 with head 53 sufficiently retracted from passage 40 so that only the portion having the flats 54 extends into said passage. Consequently, even should trigaecacc-a er be pressed, air from passage 48 will vent through passage 4o into the interior 62 of member 55, out through openings 6| into the barrel 29 which is open both at one side and the bottom. Thus, there can be no percussive reciprocation of piston 42.

As the means [8 is depressed, first the lower end of shank 5i encounters a nail at 2! so that the downward movement of element I9 is arrested while means it continues downwardly. Thus, flange 52 leaves shoulder 50 and is encountered by the lower end of cylinder 38, the head 53 moving into passage 46 to seal the same. This position is shown in Fig. 3. When the operator feels this resistance to downward travel of means is, he presses trigger .i'l so that the reciprocating movement of piston 42 will intermittently drive nail driver element downwardly relative to cylinder 38 and, thereby, institute driving of a nail at 2 l.

lhe nail-driving action begins before collar it achieves abutting engagement with barrel sleeve 21. Thus, for a short period, cylinder 38 moves downward while the first portion of the nail is being driven. When collar 64 arrests this downward movement of the cylinder, the lower end thereof will cease to move, while the nail driver element continues to be percussed downwardly. Since the collar is adjusted to 10- cats said cylinder end at a predetermined position, as the shank 5! reaches its lowermost position (Fig. 2), the flats 54 of head 53 will open passage 43 to vent the lower end of bore 39, as before described, to thereby stop reciprocation of piston 42 and automatic cessation of the naildriving operation. The operator is thus apprised of completion of the nail-driving operation and releases trigger 37 in order to conserve air.

It will be evident that the operator need not guess when to operate the trigger since impedance to downward movement tells him when to press the trigger and cessation of reciprocation of the piston tells him when to release the trigger. Thus, the operation is economical of compressed air.

In practice, the present nail-driving means has consistently driven forty to fifty nails per minute and experienced operators have driven as many as eighty per minute. Where conservation of air is not as great a factor as speed of operation, trigger 3 may be held depressed to obviate lag on the part of the operator depressing the trigger.

While the invention that has been illustrated and described is now regarded as the preferred embodiment, the construction is, of course, subject to modifications without departing from the spirit and scope of the invention. It is, therefore, not desired to restrict the invention to the particular form of construction illustrated and described, but to cover all modifications that may fall within the scope of the appended claims.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. In a nail-driving mechanism having a manually movable plunger unit embodying therein an air-reciprocated piston and said unit having a passage in one end which, when open, affords an exit for air that would, when closed, retract said piston to continue reciprocation thereof, the improvement that comprises an extension on said end of the plunger unit and provided with openings for passage of air exiting from said passage, a barrel in which said plunger unit and. extension are telescopically fitted, a nail driver element supported by said extension and having a shank extending axially into the barrel, said element being provided with a head operatively aligned and engageable with said piston and extending in a direction toward and adapted to slidingly fit the passage in the plunger unit, the end of said shank being adapted to engage a nail positioned in the path of downward movement thereof to temporarily arrest said movement upon initial telescopic contraction of the plunger unit and barrel and, upon continuance of said telescopic contraction, to enter the head of the nail driver element into the above-mentioned passage to close the same against exit of air and to, thereby, institute air-operated reciprocation of the piston, whereby the piston intermittently propels the nail driver element to drive the above-mentioned nail, and, whereby, at the end of the nail-driving movement of the piston and nail-driver element, the abovementioned head leaves said passage to open the same for escape of air and stop the nail driving movement of the piston automatically.

2. In a nail-driving mechanism having a manually movable plunger unit embodying therein an air-reciprocated piston and said unit having a passage in one end which, when open, affords an exit for air that would, when closed, retract said piston to continue reciprocation thereof, the improvement that comprises an extension on said end of the plunger unit and provided with openings for passage of air exiting from aid passage, a barrel in which said plunger unit and extension are telescopically fitted, a nail driver element supported by said extension and extending axially into the barrel, said nail driver element having a head operatively aligned and engageable with the piston and extending in a direc tion toward and adapted to slidingly fit the passage in the plunger unit, the opposite nail-driving end of the nail driver element being directed toward a nail positioned in the bottom of the barrel, whereby, when the plunger unit and barrel are telescopically extended, the above-mentioned extension supports the nail driver with its head in a position opening said passage and with its driving end spaced from said nail, whereby, upon initial telescopic contraction of the plunger unit and barrel, said nail driving end encounters the nail and is temporarily arrested thereby, whereby, upon continued telescopic contraction of the plunger unit and barrel, the head of the nail driver element enters said passage to close the same to thereby institute air-operated reciprocation of the piston so that the latter intermittently propels the nail driver element to drive the nail from the end of the barrel, and, whereby, at the end of the nail-driving movement of the piston and nail driver element, the head of the latter leaves said passage to open the same for escape of air and stop the nail-driving movement of the piston automatically.

3. In a nailing machine, nail-driving mechanism comprising a barrel having an axial bore in the lower end of which a nail is adapted to be positioned, a plunger unit telescopically movable in said barrel and having therein an air-reciprocable piston, said plunger unit having an end passage directed into said barrel, a tubular extension on said plunger unit below the passage thereof, and a nail driver element adapted to engage the nail in the barrel bore and having a flange normally engaged with said extension and CLINTON J. BACON. SAMUEL J. KENT.

Reierences Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Hellman et a1 Dec. 25, 1906 Jimerson July 26, 1927 Bayles Nov. 13, 1928 Smith Nov. 12, 1929 Kendall July 20, 1948 FOREIGN PATENTS Country Date Sweden Oct. 16, 1890 France Jan. 24, 1925 Germany Apr. 4, 1923 

